A wire-bonding apparatus typically includes a swingably provided bonding arm to which a capillary for feeding a wire such as a thin metal wire is attached, and is capable of bonding the wire to a pad of a semiconductor die by causing the bonding arm to swing to press the capillary against the pad of the semiconductor die.
In recent years, overhanging dies that protrude from a lower stack of semiconductor dies and spacers have become used as one form of die stacking. However, as an end portion of such an overhanging die is a free end and not supported by a semiconductor die or a spacer of a lower stack, bonding a wire to a pad disposed on this free end causes the overhanging die to bend by being pressed by a capillary. Therefore, in a case in which wire loops are formed after bonding, reference positions of the wire loops cannot be stabilized, and the height of the wire loops adversely becomes uneven.
Thus, Patent Literatures 1 and 2 take advantage of the fact that when a low load is applied to a bonding arm to move the bonding arm down, the bonding arm stops moving down at a position at which a capillary is brought into contact with an overhanging die, and detect the position at which the capillary is brought into contact with the overhanging die. Then, after bonding the wire, the capillary is moved up to the contact position and a wire loop is formed.